al’ lêr gy, noun - An abnormal immune response (an allergic response) to a non-harmful trigger (an allergen).

Exposure to allergens does not produce allergy symptoms in non-allergic individuals but causes mild to severe symptoms in an allergic person. These symptoms may include sneezing; watery, itchy, red eyes; a runny nose, a scratchy throat or cough. Some allergy sufferers have more symptoms involving the skin. Dry, red, itchy patches of skin called eczema can be caused by allergies. A severe allergic reaction may be expressed as hives, swelling of the lips, eyes or extremities. Life threatening allergic reactions occur when airways become swollen shut or when a rapid drop in blood pressure (shock) occurs.

There are two factors that determine if a person will have allergies: their genetic background, and their exposure to allergens. Allergies run in families. If one parent has allergies, there is about a 30 percent chance that their children will have allergies. If both parents have allergies, the likelihood goes up to about 70 percent that each child will develop allergies. The genetic background provides the potential to develop allergies, the environment provides the allergen trigger. The warm, moist climate of Houston and the Gulf Coast ensure that there are plenty of allergens year round to trigger allergy symptoms.

Anything that enters the body is potentially capable of producing an allergic response. In general, however, the most common allergic triggers are pollens (from grasses, trees, weeds), mold spores, dust mites (microscopic organisms found in house dust), insect venoms, animal danders and foods. Only two percent of the population has actual food allergies, but allergic reactions to foods are often severe and are potentially life threatening. Tobacco smoke, perfume, hair spray and the components of air pollution are generally not allergens, but their presence can make existing allergy symptoms worse.

Some allergens have a defined season. Ragweed, for example, pollinates during the fall and is a common cause of allergic symptoms from September through Thanksgiving. Other allergens have less defined seasons and their levels will fluctuate throughout the year.

Allergy sufferers are more likely to also suffer from the following conditions:

		Frequent Sinus Infections
		Ear Infections
		Asthma and Bronchitis
		Eczema
		Sleep Disorders
		Migraine Headaches

Children with allergies are sometimes mistakenly diagnosed with ADHD due to their allergy symptoms interfering with their ability to concentrate in school.

Your home, school or workplace may contain substances that can cause an allergic reaction. These environmental substances include dust or dust mites, animal dander (mostly cats), mold spores, mildew or pollen. While pollen allergies usually occur in certain seasons, these other substances can cause allergy problems all year round.

While avoidance is the best solution in most cases, some causes of symptoms, such as pollen, molds, and dust mites, cannot be eliminated. Exposure can be reduced, however, by environmental control measures prescribed by your allergist.

When it comes to allergies, living in Houston makes treatment harder because the true allergy to dust mites, mold or pollen is superimposed on the non-allergic effects of the pollution, ozone and humidity. Many patients say they feel great when they travel elsewhere, only to have symptoms come roaring back as soon as they return. So, if you're going to live in Houston because of your job, or because this is where your loved ones are, then successfully treating allergies may require you to be a bit more aggressive. That means paying equal attention to avoiding dust mites or mold that you're allergic to, avoiding non-allergic triggers (e.g., cigarette smoke, perfume, etc), and seeking medical help.

DUST AND DUST MITES
The following information is courtesy of Mission Allergy:

Dust mites are microscopic creatures that live in pillows, mattresses, blankets, carpets, and other soft materials. They are often thought of as insects, but are actually tiny arachnids, relatives of spiders and ticks. They do not live on people, but live near them. Their food is the dead skin scales that we all shed every day.

Dust mites avoid the light, and require at least 50% relative humidity to survive. They are therefore plentiful in soft materials, such as pillows, mattresses, and blankets, where they can burrow into the fabric to get away from the light. Beds provide the warmth, darkness, high humidity, and shed skin scales that mites crave, and they are the source of the biggest mite exposure for most of us. A mattress may contain over a million dust mites. A female mite lays about 60 eggs in her lifetime. Each mite lives for about 80 days, during which time it produces one thousand allergy-causing waste particles.

Live mites themselves are not inhaled. Rather, it is the waste particles that they have produced, and the body fragments of dead dust mites, that become airborne, are inhaled and cause allergy symptoms. This is because mites do not live in the air, but are burrowed in soft materials. Mite waste particles become briefly airborne when one walks on a carpet, sits on an upholstered chair, places one's face on a pillow, makes a bed, or otherwise disturbs the soft materials where the dust mites are living.

POLLEN
After a long Houston summer, we're all ready for cool evenings. But when nighttime temperatures drop below 70 degrees, and humidity drops below 70%, ragweed starts to grow. Ragweed is the main source of allergic misery for those who suffer in September and October. Ragweed will continue to make pollen until early November unless we get an early freeze.

Interestingly, several foods cross-react with ragweed. If you are allergic to ragweed, you may experience itching or tingling of the lips or tongue when you eat cantaloupe, watermelon or bananas while ragweed pollen counts are high. Interestingly, by cooking the related food, heat will alter the structure of the antigen, usually making it non-allergenic. Drinking chamomile tea may cause a similar reaction.

Ragweed puts out more pollen in the mornings than in the evenings, so if you're allergic to it, save outside activities for late afternoon or after a heavy rain, when pollen levels are lower.

We've been waiting all summer to roll down the windows in our car, but if you're allergic to ragweed, this is asking for trouble. Take advantage of the filtering system in your car's HVAC system to keep symptoms in check. If you have an indoor dog that goes outside to play for a while, consider giving him/her a bath; dog fur has a static charge which acts as a transport mechanism to bring in all sorts of pollen.

Ragweed is named for the raggedy shape of its leaves. It's not a very pretty plant; still, what it lacks in beauty, it makes up for in potency. One ragweed plant can put out over one billion grains of pollen! Its scientific name, Ambrosia, was the delicious food eaten by the mythical Greek gods to make them live forever.

Remember, if you're on one of those preventative steroid nose sprays (e.g., Nasonex, Rhinocort, or Nasacort), start it soon so it will be working when ragweed pollen hits its peak.

Often, patients come in telling us what foods they are allergic to on the basis of allergy testing done years before. It’s quite possible that they are not allergic to those foods at all. Allergy testing is very accurate when we test for dust mites, mold, and pollen. But it’s less accurate when we test for foods. Years ago, many allergists, even those board certified by the American Board of Allergy and Immunology, would tell patients to avoid foods on the basis of skin test results alone. The most reliable way to confirm a food allergy is with a food challenge. This test involves giving a capsule to a patient that contains either the food that they suspect or a placebo. To ensure the objectivity and validity, the patient (and often the doctor) doesn’t know which capsule they receive.

Reactions can range from immediate itching or swelling of the lips and/or tongue, to hives, coughing, and wheezing. These usually happen within a few minutes after eating the food, sometimes up to an hour. But some true food allergies cause stomach cramping and diarrhea hours later. Unfortunately, there are no safe and effective forms of allergy shots or allergy drops for food allergy at this time. Food allergies can be life-threatening, especially if one is allergic to peanuts, shellfish, or tree nuts. Besides avoiding these foods, the doctor should prescribe an injector device with epinephrine (adrenaline) to be available at all times. Make sure that the one you buy has at least 12 months left until it expires. You often get the freshest at 24-hour pharmacies. Still, if anaphylaxis occurs and all you have is an expired device, good research shows that it’s still worthwhile using it.

A careful distinction must be made between “food allergy” and “food intolerance.” Many people have lactose intolerance, which causes gastrointestinal symptoms upon eating milk products. Other examples of food intolerance include headaches from drinking wine or a runny nose from eating spicy foods.

Two other common allergies are aspirin allergy and iodine allergy.

ASPIRIN ALLERGY
Over the past five years, we have been getting more referrals from cardiologists at Methodist, St. Luke’s and Memorial Hermann asking us to desensitize their patients to aspirin. There has not been an increase in aspirin allergy, but new cardiac stents that could save a patient the risk of open heart surgery recommend that you take aspirin afterwards to help keep the stent open. In the past, aspirin desensitization was done only in the hospital. Now, however, the medical literature states that it is safe to desensitize aspirin patients in a physician’s office.

Interestingly, when we received the first call from cardiology practices, they were delighted to find an allergist, who would do this procedure. It is very time consuming and does not pay well, plus it is not without risk; that is my guess as to why more allergists do not feel comfortable performing aspirin desensitization. One of our favorite phone calls to make is to the referring cardiologist at the end of the day, telling them that the patient has successfully been desensitized to aspirin. The best reply back was a backhanded compliment: “You just saved this lady cardiac bypass surgery. Not bad for an allergist.”

There are actually two completely distinct ways to become allergic to aspirin. Aspirin triggers asthma in many people, and causes hives in others. Besides cardiac reasons, we have also performed aspirin desensitization to help people with arthritis be able to take effective pain medications.

If you or your loved one are allergic to aspirin and need to treat that allergy, we will be happy to help out. We have met a lot of interesting patients this way and they often refer family members for treatment of routine allergies to us. The comment we frequently hear is that if we are qualified enough to desensitize aspirin allergic patients, we can certainly handle asthma, rashes, headaches, stuffy noses, and sneezing.

IODINE ALLERGY
At least once a week, we hear a patient tell us that they are scared to eat fish because they had an allergic reaction to iodine. The next part of the story involves the Radiology procedure they underwent when they had the reaction. Let’s untangle two myths and shed some light on this:

1) Radiocontrast Media (RCM) that contains organic iodine may cause adverse reactions such as urticaria, angioedema, bronchospasm, laryngospasm and shock. These reactions are not truly allergic in origin. Instead, a non-allergic pathway triggers what looks exactly like an allergic reaction. While we don’t know the exact mechanism, it is apparently related to the high osmolarity (concentration of particles) of these agents. If you have had this type of reaction and need another procedure done, your physician will probably recommend a lower osmolar preparation to decrease the risk of another reaction.

The risk can be further decreased by pre-medicating with antihistamines (e.g., Allegra, Claritin/Clarinex or Zyrtec) and steroids (e.g., prednisone). I don’t recommend Benadryl anymore for outpatient pre-medication protocols. The risk of tolerating the procedure just fine, but then falling asleep and crashing your car into a tree on the way home must also be considered. Why would you fall asleep? Don't forget that most over the counter sleeping pills are made of diphenhydramine (the active ingredient in Benadryl).

2) Seafood may contain iodine. However, seafood allergy is not caused by iodine; rather, to specific proteins in fish and shellfish (e.g., parvalbumin, tropomyosin) that also do not contain iodine. Thus, fish or shellfish allergy does not indicate a sensitivity or allergy to iodine.

So how did the two myths get tangled? Allergic reactions tend to occur in people who already have other allergic reactions. So the person who has allergies (e.g., shrimp) is at higher risk to have another unrelated allergic reaction than the person with no history of allergies.

Many thanks to the American Academy of Allergy, Asthma and Immunology for providing this update. Their website is a terrific source for physicians and health consumers.